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Von Willebrand Factor Antigen

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Updated Test Information:

Test Description
Von Willebrand Factor Antigen
Synonym(s)

Factor 8 Related Antigen, Factor VIII Related Antigen, UOW1513
Test ID
VWFAG
General Information

Von Willebrand Factor (VWF) antigen is an immuno-turbidimetric assay based on the agglutination of latex microparticles coated with antibodies specific for VWF added to the patient's plasma. The antigen-antibody reaction increases the turbidity of the reaction medium which is measured photometrically. The degree of turbidity and absorbance is directly related to the function of VWF level present in the patient's plasma.


Von Willebrand disease is diagnosed with a group of tests (factor VIII activity, von Willebrand factor antigen, von Willebrand factor activity, collagen binding assay and multimer analysis) in the context of the patient's medical history and clinical presentation. Von Willebrand antigen can be used to monitor therapeutic efficacy of treatment with DDAVP (desmopressin) or von Willebrand factor concentrates in patients with vWD.


Like all antigenic tests, the vWF assay cannot detect the rare type 2 von Willebrand disease variants whose level of VWF antigen is normal.
Container Type

3 mL or 5 mL Light Blue Citrate Tube
Specimen Type

Plasma
Specimen Requirements

Sample must be centrifuged, aliquoted and frozen within 4 hours of collection
Specimen Collection / Processing Instructions

MUST PROCESS WITHIN 4 HOURS OF COLLECTION
Platelet poor Coag Citrate Specimen processing:
1. Gently invert tube 2-3 times prior to placing in Centrifuge
2. Centrifuge Citrate whole blood at 4500 rpm for 10 minutes
3. Carefully pipette plasma, avoiding the platelet/buffy coat into a plastic vial
4. Centrifuge plasma at 4500 rpm for 10 minutes
5. Pipette the plasma to a plastic vial, leaving the bottom 0.25 mL undisturbed
6. Freeze plasma immediately and transport frozen
Minimum Sample Volume

1 mL
Stability

Frozen
Limitations

The presence of rheumatoid factor may lead to an over-estimation of the vWF level. The extremely rare presence of anti-bovine albumin or anti-rabbit antibodies in certain subjects may lead to an over-estimation of vWF level.


This assay is insensitive to hemoglobin (up to 5g/L), bilirubin (up to 150 mg/L) and unfractionated heparin and low molecular weight heparin (up to 2 IU/mL).
Department (code)

Coagulation
Methodology

 Optical, Stago STA LIA vWF Antigen assay
Testing Schedule

Tuesday and Friday. Reported by end of day.
CPT Code(s)

85246
Reference Range

Units: %

Male/Female


50-200


Effective date: 10/03/2006
Performing Lab

UW
LOINC Code(s)